49 
Chapter VII. 
THE DOLERITES. 
The doleritic type of rock has been found in practically the same localities as the 
Beacon Sandstone, and it will, therefore, be convenient to consider the localities in 
the same order as before. The dolerite of Depot Nunatak is the highest point from 
which rock of any kind has been collected in South Victoria Land. Dolerites occur here 
at an elevation of 7000 feet, and, at the foot of Knob Head Mountain, about 30 miles 
nearer the coast, they have also been seen only 3500 feet above sea-level. There is 
no evidence of the presence 
of surface-outpourings, and 
as no vesicular or scoria- 
ceous rocks were observed, 
even in the moraines, it 
would appear that these 
rocks are wholly intrusive. 
Depot Nunatak (A.) 
(Figs. 24 & 25). 
Lieutenant A. B. 
Armitage on the first 
journey through the Royal 
Society Range obtained 
weathered dolerite - frag- 
O 
ments (632, 633) at Depot 
Nunatak, and at the same time Engineer-Lieutenant R. W. Skelton photographed 
Fig. 24. — Depot Nunatak, from the East. 
great 
columns 
through the snow. 
The 
the parent rock which rises as a mass of 
rock (662)’ is an outlier, and protrudes through the snow at an elevation of about 
6000 feet. The nunatak rises to a height of nearly 500 feet above the snow and 
is exceedingly columnar throughout. Some of the columns are 12 feet in diameter 
and, though broken, give the impression that they extend the whole height of the 
cliff. Depot Nunatak is 60 miles from the coast and is entirely cut of}' from the 
dolerite 
capping 
the sandstone eight miles to the east. 
The Hill B x . 
Here the dolerite caps the sandstone and produces a cliff which rises vertically 
for more than 500 feet. This cliff forms the east side of the South-west Arm for 
a length of ten miles. As before, the columns which go to make up the sheet are 
VOL. I. 
H 
